# How to determine gauge of winding wire

#### beatsal

Joined Jan 21, 2018
302
I want to rewind a motor but do not have a means to measure the gage of the existing wire. Is there any way to determine the gage? I only have foot-rule

Joined Jul 18, 2013
25,469
You really need a digital micrometer, also you need to remove the enamel for accuracy.
Cut off a small piece and take into either a rewind shop or a local engineering shop, they should measure it for a favour.

#### Alec_t

Joined Sep 17, 2013
12,904
Welcome to AAC!
If all you have is a 1 foot rule, here's a way :-
1) Cut off a 6" length of the wire (not critical),
2) Bend the wire into an 'L' shape,
3) Mark off a 1" line on a piece of card,
4) Place one leg of the L, to act as an axle, at one end of the 1" mark,
5) Roll the 'axle' along the mark, the other leg acting as an indicator (clock hand).
6) Count the number n of rotations to reach the other end of the mark.
7) Do the maths. Wire diameter d = 1"/(n*π*).

The answer won't be as accurate as Max's method, but should get you close to the nearest standard wire gauge size.

#### Beau Schwabe

Joined Nov 7, 2019
120
Another method is to wind the wire onto something as tight (close together) as you can and scan it with a flat bed scanner.... noting the DPI resolution of your scanner, count the number of turns and number of pixels to determine a relatively accurate diameter of the wire. Once you know the diameter of the wire you should be able to determine the gauge.

#### MrChips

Joined Oct 2, 2009
26,530
Compare it visually with something you have at hand.
For example,

Joined Jul 18, 2013
25,469
BTW, The enamel accounts for ~ 2 to 3 thou of the diameter.

Joined Jul 18, 2013
25,469
If in N.A. Home Depot have a mic that is under $15.00, you could even take the wire in and 'Try it out" #### cmartinez Joined Jan 17, 2007 7,750 This file might come in handy... #### Attachments • 290.7 KB Views: 7 #### MrChips Joined Oct 2, 2009 26,530 Try winding about 20-100 turns with turns very tightly together on a hollow tube and measure length of coil divided by number of turns. #### sagor Joined Mar 10, 2019 704 Why mess around when you can get it for$10.00 ?? https://www.amazon.com/Digital-Caliper-Adoric-Calipers-Measuring/dp/B07DFFYCXS
crid=2IZI0CPLTZ93S&keywords=digital+micrometer&qid=1654975792&sprefix=digital+micrometer,aps,212&sr=8-3

Also if getting to such as rewinding it will probably come in handy in the future for many reasons.
That is ok for general use, but with a measuring error of +/- 0.2mm it is hard to measure fine wires with that device. There are more accurate digital calipers out there. I have one that is all metal, and resolution and error is 10 times better. I also have one like you posted, but use it for general measurements only.
Similar to:
https://www.amazon.com/VINCA-DCLA-0.../B017KUC6XQ/ref=psdc_4989299011_t3_B07DFFYCXS

Joined Jul 18, 2013
25,469
That is ok for general use,
Agree, Mine is a Mitutoyo, but I use it almost every week.

I also have my old Moore & Wright from the '60's !

#### cmartinez

Joined Jan 17, 2007
7,750
Agree, Mine is a Mitutoyo, but I use it almost every week.

I also have my old Moore & Wright from the '60's !

View attachment 269247
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